1. Field of the Invention
The present invention relates generally to an edge light illuminator arrangement and particularly to a device for supplying incident light to an edge light panel.
2. Prior Art
This type of edge light panel includes a linear form light source on the incident end surface side of the edge light panel for feeding incident light to it.
In order to supply this incident light, use is generally made of reflector means which surrounds the linear form light source. Thus, the incident light supply device is made up of a linear form light source and a reflector or reflection sheet.
This is typically set forth in JP-Kokai-1-90085, according to which the linear form light source is surrounded and covered with reflector means built up of a silver reflection film over a region of 180.degree. to 270.degree. except the incident end surface side of the edge light panel. This incident light supply device is designed to reduce emission of the light emanating from the light source, and to focus the light source light on the incident surface of the edge light panel, whereby the amount of the light incident on the edge light panel can be increased as much as possible. In the art, this may be called the light-focusing system.
Indeed, the incident light supply device relying on this light-focusing system achieves an about 30-40% increase in the luminanee of illumination, when compared with a simple arrangement in which an opposite array of reflectors are used for the incident end surface, and so is excellent in itself. In combination with some improvements in the edge light panel and in the reflection plane, this achieves an average luminanee of, say, 950-1,150 cd/m.sup.2, when used as an edge light illuminator for, e.g., a liquid crystal backlight.
This intensity of illumination is particularly well suited for a liquid crystal backlight used in association with a monochromic display panel. However, on the other hand, it provides insufficient light intensity for a liquid crystal backlight used in association with a color display panel, and so its use to this end is almost impossible.
This is because the liquid crystal backlight used in association with a color display panel is required to have an intensity of illumination at least twice or treble, preferably several times as large.
One way, this desired increase in luminance may be achieved is by increasing the number of linear form light sources used. In order to be used with the liquid crystal backlight mentioned above, however, the edge light illuminator should be made as thin as possible. This need for a thin, compact design runs counter to the provision of additional space necessary to increase the number of light sources. Additionally, power saving is also needed so that the equipment may be made more portable. The increase in the number of light sources is again contrary to such power saving and portability concerns, and accordingly, is said to be unsuitable for improving luminance.
In view of such situations as mentioned above, it is therefore an object of this invention to provide an incident light supply device for an edge light panel, which can be thin, save power and attain a drastic increase in the intensity of illumination.